The present invention is related to display assemblies usable for mounting and providing illumination for LCD (liquid crystal display) devices. More specifically, the present invention is related to such display assemblies which provide suitable backlighting for LCD devices.
Typically, LCD's have a general plate-type configuration and are electrically connected to driver electronics such that various graphic patterns can be selectively provided when the LCD is viewed from either its top or bottom surface. LCD assemblies may be configured just to utilize ambient reflected light, but typically these assemblies are unsuitable for low levels of ambient light. In such situations, selective electrical backlighting of the LCD is typically provided. Various techniques are utilized to provide uniform electrical backlighting of the LCD.
Generally the LCD is mounted in a display housing and is positioned within the housing by an LCD carrier to which the LCD is mounted. The carrier is used to properly orient the LCD with respect to the housing and other components. The carrier and LCD are then mounted to a printed circuit board, containing the LCD drive electronics, which is mounted to the display housing.
Typically, assemblies such as those described above are relatively complex and require a number of individual parts to insure both uniform lighting of the LCD and proper mounting of the LCD within the display housing. An example of one such previous display assembly is illustrated in an article entitled "An LCD Display Assembly", pages 51-52 of Volume 2, Motorola Technical Developments, January, 1982. The display assembly illustrated in this article utilizes numerous mounting structures and requires complex assembly since, until the LCD and carrier are mounted to the printed circuit board, a large number of assembly components are only loosely positioned in their appropriate places. In addition, the above-noted assembly would require, if possible, additional structure in order to accomplish uniform backlighting of the LCD by any point light source. Also, typically fixed graphic legends are provided and associated with the LCD display, wherein such graphics are desired to be constantly illuminated, as contrasted with the selective LCD visual display to be produced. Providing illumination for these graphics would typically require separate additional light illumination sources and/or structure which would further complicate the LCD assembly.
While some prior systems have proposed utilization of wedge-shaped light pipe structures to obtain uniform backlighting of LCD devices, providing such an additional wedge-shaped light pipe structure would appear to even further complicate assemblies such as that shown in the above-noted Motorola article.